As life span increases in the US population and more women choose demanding careers deferring childbearing to later years, age-related health problems become a matter of national concern. There is an urgent need to understand the biological basis of the aging process and the basis of reproductive senescence in humans. Research on model organisms such as Drosophila helped to uncover several lifespan-regulating genes; however, genetic pathways that postpone aging are far from being fully understood. We recently discovered that the gene period (per), a well-known component of the biological clock, affects longevity and fertility in female Drosophila. There is extensive knowledge of this gene and its protein product; therefore, tools are available to research its role in aging. We plan to verify and expand our initial findings and address several new questions: 1) Are per effects on lifespan gender-specific? 2) Does per affect reproduction and life span in both virgin and mated females? 3) Which physiological systems are involved in per action? Results of these proposed studies will provide the first insights into the mechanisms underlying the action of the clock gene period in the investigated phenotype and allow us to develop a research project grant (R01) aimed at understanding the molecular pathways underpinning female reproductive aging. Our goal is consistent with NIA plans to accelerate efforts to discover additional longevity-related genes and to characterize their biological function. Given the conserved functions of per in biological timing from flies to humans, knowledge gained concerning the mechanism of action of this gene may provide important contributions to our understanding of reproductive and chronological aging in humans.